JP7194921B2 - Semiconductor device manufacturing method - Google Patents

Description

The present disclosure relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device using soluble resin.

In recent years, electronic parts and devices have become smaller, more sophisticated, and more multifunctional. A narrower pitch is achieved.

Flip-chip mounting is generally known as one of the methods for mounting a semiconductor element with a large number of pins and a narrow pitch on a substrate. In this flip-chip mounting, protruding electrodes formed on electrode pads of a semiconductor element and connection terminals of a substrate are joined and electrically connected by, for example, heating, pressurization, or application of ultrasonic waves.

Solder bumps formed by, for example, a wire bonding method, an electrolytic/electroless plating method, a transfer method, or the like are known as the projecting electrodes. However, the wire bonding method has a limit in narrowing the pitch. Further, in electrolytic/electroless plating and transfer method, narrowing of the pitch tends to cause bridge defects. A bridging defect is a phenomenon in which adjacent solder bumps melted in the pressure process and the heating process during mounting are connected to each other.

As an improvement measure for narrowing the pitch, for example, in Patent Document 1, an opening having an inversely tapered cross-sectional shape (which may be called a cavity) is formed in a resist by photolithography, and the opening is plated. A method of forming metal bumps by treatment is disclosed.

Here, the outline of the manufacturing method of the semiconductor device of Patent Document 1 will be described with reference to FIGS. 5A to 5C. 5A to 5C are schematic diagrams for explaining the manufacturing method of the semiconductor device described in Patent Document 1. FIG. 5A to 5C schematically show cross sections of the semiconductor device.

First, as shown in FIG. 5A, an insulating film 12, an aluminum pad 13 and a protective film 14 are formed on a silicon substrate 11. Then, as shown in FIG. After that, Ti (titanium), Pt (platinum), W (tungsten), Pd (palladium), etc. are vapor-deposited to a thickness of 5000 to 8000 Å to form a barrier metal 15 consisting of two to three layers.

Next, a negative type resist 17 is applied on the barrier metal 15 . The film thickness of the resist 17 is, for example, 15 to 20 μm. Then, during pattern formation, the exposure time is set longer than normal (in other words, overexposure) to form an opening having a reverse tapered cross section in the resist 17 as shown in FIG. 5B. Next, using the resist 17 as a mask, the opening is electrolytically plated with an Au (gold) electrolytic plating solution. Thereby, as shown in FIG. 5C, a bump 16 having a forward tapered cross-sectional shape is formed.

JP-A-4-217324

When forming protruded electrodes on a large-diameter wafer using the method of Patent Document 1 described above, in-plane uniformity is important in the process of forming the resist film thickness, the exposure process, and the development process. However, especially in the development process, it is difficult to ensure not only in-plane uniformity but also reproducibility.

In addition, since it is important for the projecting electrodes to absorb the stress during mounting, it is advantageous to form the projecting electrodes in a sharp shape. However, in order to achieve a sharp shape, the shape of the opening of the resist must be a reverse tapered shape, and the stabilization of the shape of the projecting electrode in the exposure process and the development process has become a more important issue.

An object of one aspect of the present disclosure is to provide a method for manufacturing a semiconductor device that can realize a bump electrode with a stable shape.

A method for manufacturing a semiconductor device according to an aspect of the present disclosure includes a resin forming step of coating a surface of a semiconductor element including a plurality of electrode pads with a cured resin, forming projections of the cured resin on the electrode pads, A projection forming step of curing the projection, a resin supply step of coating the projection with the plating solution resistant resin, and removing a part of the plating solution resistant resin to form a coating on the surface of the plating solution resistant resin. a resin exposing step of exposing a portion of the protrusion; a dissolving step of forming a cavity in the plating solution resistant resin by removing the cured resin corresponding to the protrusion; and plating the cavity. A filling plating step and a resin removing step of removing the plating solution resistant resin are included.

According to the present disclosure, it is possible to realize a projection electrode with a stable shape.

Schematic diagram for explaining a resin forming step according to Embodiment 1 of the present disclosure Schematic diagram for explaining a projection forming step according to Embodiment 1 of the present disclosure Schematic diagram for explaining a projection forming step according to Embodiment 1 of the present disclosure Schematic diagram for explaining a projection forming step according to Embodiment 1 of the present disclosure Schematic diagram for explaining the resin supply process according to the first embodiment of the present disclosure Schematic diagram for explaining a resin exposing step according to Embodiment 1 of the present disclosure Schematic diagram for explaining the dissolving step according to Embodiment 1 of the present disclosure Schematic diagram for explaining the plating process according to the first embodiment of the present disclosure Schematic diagram for explaining a resin removing step according to Embodiment 1 of the present disclosure Schematic diagram for explaining the residual film removing step according to the second embodiment of the present disclosure Schematic diagram for explaining the residual film removing step according to the second embodiment of the present disclosure Schematic diagram showing an example of the shape of a projecting electrode according to Embodiment 4 of the present disclosure Schematic diagram showing an example of the shape of a projecting electrode according to Embodiment 4 of the present disclosure Schematic diagram showing an example of the shape of a projecting electrode according to Embodiment 4 of the present disclosure Schematic diagram showing an example of the shape of a projecting electrode according to Embodiment 4 of the present disclosure Schematic diagram for explaining the manufacturing method of the semiconductor device of Patent Document 1 Schematic diagram for explaining the manufacturing method of the semiconductor device of Patent Document 1 Schematic diagram for explaining the manufacturing method of the semiconductor device of Patent Document 1

Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings. In addition, the same code|symbol is attached|subjected about the component which is common in each figure, and those description is abbreviate|omitted suitably.

(Embodiment 1)
In the method of manufacturing a semiconductor device according to the first embodiment of the present disclosure, a resin forming process, a protrusion forming process, a resin supplying process, a resin exposing process, a dissolving process, a plating process, and a resin removing process are performed in this order.

1A to 1I are diagrams for explaining the method for manufacturing a semiconductor device according to this embodiment. 1A to 1I schematically show cross sections of semiconductor devices.

First, the resin forming process, which is the first process, will be described with reference to FIG. 1A.

As shown in FIG. 1A, a plurality of electrode pads 2 are formed on the surface of semiconductor element 1 .

In the resin forming step, first, as shown in FIG. 1A, a seed layer 3 is formed so as to cover the entire surface of the semiconductor element 1 including the electrode pads 2 .

The seed layer 3 is used as a base for forming electrolytic plating. Examples of materials for the seed layer 3 include Ni (nickel), W (tungsten), Cr (chromium), Cu (copper), Co (cobalt), Ti (titanium), and Pd (palladium). The thickness of the seed layer 3 (length in the vertical direction in the drawing) is, for example, 0.01 to 1 μm.

Next, as shown in FIG. 1A, the entire surface of the seed layer 3 is covered with a soluble ultraviolet curable resin 4. Then, as shown in FIG.

At this time, the soluble ultraviolet curable resin 4 (an example of a curable resin) is applied thinly and uniformly by, for example, spin coating or a coater. Examples of the soluble ultraviolet curable resin 4 include acrylic ultraviolet curable resins. The thickness of the soluble ultraviolet curable resin 4 is, for example, about 1 to 20 μm, and is set according to the shape and height of the projecting electrodes 7 (see FIG. 1I) to be finally formed. Also, the material of the soluble ultraviolet curable resin 4 is, for example, an ultraviolet curable resin soluble in alcohol or a solvent other than alcohol.

In the present embodiment, the case of using the soluble ultraviolet curable resin 4 that is cured by irradiation with ultraviolet rays will be described as an example, but a resin that is cured by a method other than irradiation with ultraviolet rays may be used.

Next, with reference to FIGS. 1B to 1D, the process of forming projections that follows the process of forming resin will be described.

As shown in FIG. 1B, an imprint mold 5 (an example of a transfer mold) is provided with recesses 5a corresponding to the positions of the respective electrode pads 2. As shown in FIG. The recess 5a is, for example, conical or pyramidal.

In the projection forming step, first, as shown in FIG. 1B, each concave portion 5a and each electrode pad 2 are aligned.

Next, as shown in FIG. 1C, the imprint mold 5 is pressed (in other words, pressurized) against the soluble ultraviolet curable resin 4 .

Next, in the state shown in FIG. 1C, the soluble UV-curable resin 4 is cured by irradiating the surface of the soluble UV-curable resin 4 with UV rays. Arrow A in FIG. 1C indicates the irradiation direction of ultraviolet rays.

After the ultraviolet irradiation, the imprint mold 5 is released from the semiconductor element 1 .

After releasing the imprint mold 5, as shown in FIG. 1D, a convex soluble UV-curable resin 4, that is, a projection 4a of the soluble UV-curable resin 4 (hereinafter simply referred to as "projection 4a") is formed. . The shape of the protrusion 4 a is the same as the shape of the recess 5 a of the imprint mold 5 . A residual film portion 4b of the soluble ultraviolet curable resin 4 (hereinafter simply referred to as "remaining film portion 4b") is formed in a portion other than the protruding portion 4a.

Note that the soluble UV curable resin 4 may be heated before the imprint mold 5 is pressed against the soluble UV curable resin 4 . As a result, the fluidity of the soluble ultraviolet curable resin 4 is improved when the imprint mold 5 is pressed against it, and the protrusions 4a can be formed in a more stable shape. Furthermore, the imprint mold 5 may be applied to the soluble ultraviolet curable resin 4 in a vacuum. As a result, entrainment of voids can be suppressed, and occurrence of pattern defects can be suppressed.

Further, the soluble ultraviolet curing resin 4 may be heated before the imprint mold 5 is released from the semiconductor element 1 . As a result, it is possible to prevent the soluble ultraviolet curable resin 4 from adhering to the imprint mold 5 at the time of mold release, and to improve mold releasability.

The temperature at which the soluble ultraviolet curable resin 4 is heated during pressing and releasing is preferably about 40 to 90 degrees.

As the material of the imprint mold 5, for example, acrylic resin, silicone resin, polydimethylsiloxane (PDMS), quartz, glass, or the like can be used. In addition, since it is necessary to UV-cure the soluble UV-curable resin 4 in a state where it is pressure-transferred by the imprint mold 5 (for example, the state shown in FIG. 1C), the material for the imprint mold 5 is A transparent material having a transmittance of 50% or more is preferred.

Alternatively, the surface of the imprint mold 5 may be subjected to mold release treatment in advance. This can prevent the soluble ultraviolet curable resin 4 from adhering to the imprint mold 5 when the mold is released. Resins such as silicone and fluorine are preferable as the material used for the release treatment.

Next, with reference to FIG. 1E, the resin supplying process that follows the projection forming process will be described.

In the resin supply step, as shown in FIG. 1E, the projecting portion 4a and the residual film portion 4b are covered with a plating resistant resin 6. Then, as shown in FIG. As the plating-resistant resin 6, for example, a material such as a resist, which has plating resistance, can be used.

At this time, the plating resistant resin 6 is provided thinly and uniformly by, for example, spin coating or a coater. The thickness of the plating-resistant resin 6 (the length in the vertical direction in the figure) is preferably about 1 to 20 μm, for example, so that the removal process in the resin exposing process described later can be performed in a short time.

In addition, since the plating resistant resin 6 will be immersed in the plating solution in the plating process, which will be described later, a resist resistant to the plating solution is used, and the shape can be maintained even during the plating process.

Next, with reference to FIG. 1F, the resin exposing step that follows the resin supplying step will be described.

In the resin exposing step, as shown in FIG. 1F, the plating resistant resin 6 and the top of each protrusion 4a are removed by a mechanical method or a chemical method, and a horizontal section (hereinafter also referred to as an exposed surface) of each protrusion 4a is exposed. is exposed on the surface of the plating resistant resin 6.

The thickness of the protruding portion 4a shown in FIG. 1F (the length in the vertical direction in the figure) corresponds to the height of the protruding electrode 7 (see FIG. 1I) formed in the plating process described later.

Moreover, when the projection part 4a is conical, the exposed surface becomes circular. In that case, it is preferable that the circular diameter is at least about 1 μm. Moreover, when the projection part 4a is pyramid-shaped, the exposed surface becomes a polygon. In that case, it is preferable that the diameter of the circumscribed circle of the polygon is at least about 1 μm. The reason why the diameter or the diameter of the circumscribed circle is about 1 μm is that it is necessary to permeate a liquid such as a solvent in the plating process, which will be described later.

Moreover, examples of the mechanical method include a method of grinding and polishing the resin using a predetermined tool. In addition, as the above scientific method, for example, the gas and resin are chemically reacted by irradiation with ultraviolet rays, etc., and the resin is peeled off by photoexcited ashing, or the gas is converted to plasma with a high frequency or the like, and the resin is peeled off by irradiating the plasma. Examples include, but are not limited to, plasma ashing.

Next, the dissolving process that follows the resin exposing process will be described with reference to FIG. 1G.

In the dissolving step, each protrusion 4a shown in FIG. 1F is dissolved and removed. Thereby, as shown in FIG. 1G, each cavity 6a is formed in the plating resistant resin 6. Next, as shown in FIG.

For example, using a spinner or a paddle, the exposed surface of each protrusion 4a is immersed in the solvent. As a result, the solvent permeates into the inside from the exposed surface of each protrusion 4a, and each protrusion 4a is dissolved and finally completely removed.

The surface of the seed layer 3 on the electrode pad 2 is provided with a protrusion 4a and a plating-resistant resin 6 (see, for example, FIG. 1F). It has the property of not being dissolved by solvents. Therefore, in the dissolution step, as shown in FIG. 1G, a hollow portion 6a having the same shape as the protrusion 4a (for example, a truncated cone shape or a truncated pyramid shape) is formed on the surface of the seed layer 3 on the electrode pad 2. be done.

Next, the plating process that follows the dissolving process will be described with reference to FIG. 1H.

In the plating step, the hollow portion 6a shown in FIG. 1G is plated to form the projecting electrodes 7 as shown in FIG. 1H. The projecting electrode 7 has the same shape as the cavity 6a.

As the plating treatment, for example, an electrolytic plating method can be used. Specifically, each cavity 6a is immersed in the electroplating bath while the electrodes provided in the electroplating bath and the seed layer 3 are connected to a power supply, and an energization process is performed. As a result, each cavity 6a is filled with the plating solution.

As the plating solution, for example, a bottom-up type fill plating solution made of Cu (copper), Au (gold), or the like is preferable. By using such a plating solution, it is easy to inject the plating solution into each cavity 6a even if each cavity 6a is minute or has a complicated shape.

Next, with reference to FIG. 1I, the resin removal process that follows the plating process will be described.

In the resin removing step, the plating resistant resin 6 shown in FIG. 1H is removed. As a result, as shown in FIG. 1I, each projecting electrode 7 is exposed.

As a method of removing the plating resistant resin 6, for example, a method of immersing the plating resistant resin 6 in a stripping solution and peeling it off from the semiconductor element 1, or a method of protecting each projecting electrode 7 with a mask and then removing the plating resistant resin by dry etching. A method of removing 6 and the like can be mentioned.

As described above, according to the method for manufacturing a semiconductor device of the present embodiment, projecting electrode 7 is formed based on the shape of concave portion 5 a of imprint mold 5 . Therefore, it is possible to easily stabilize the area and shape of an arbitrary horizontal cross section of the protruded electrode 7, which has been difficult in photolithography for a large-diameter wafer.

(Embodiment 2)
A second embodiment of the present disclosure will be described.

After the above-described projection forming step is completed, residual film portions 4b are formed on both sides of each electrode pad 2 in addition to each projection portion 4a, as shown in FIG. 1D. This residual film portion 4b remains as shown in FIG. 1I even after the resin removal step described above.

In terms of the function of the semiconductor device, there is no problem even if the residual film portion 4b remains. However, for example, when the semiconductor device is packaged, there is a problem that adhesion with resin such as underfill is deteriorated and reliability is lowered. Further, for example, in the case where the semiconductor device has a hollow structure, there is a problem that droplets are generated due to heat treatment at a high temperature or a dew condensation test.

In order to avoid such a problem, in the present embodiment, the residual film portion removing step of removing the residual film portion 4b is performed after the projection forming step described above.

In the remaining film portion removing step, the remaining film portion 4b shown in FIG. 1D is removed by a method such as dry etching.

As a result, as shown in FIG. 2, only the protrusions 4a corresponding to the positions of the electrode pads 2 remain on the seed layer 3, and the next step is performed. Therefore, after the resin removing step, which is the final step, only the projecting electrodes 7 are formed on the seed layer 3 as shown in FIG. Therefore, the problem mentioned above can be eliminated.

(Embodiment 3)
A third embodiment of the present disclosure will be described.

In the second embodiment, the case where the residual film portion removing step is performed after the protrusion forming step has been described as an example, but the residual film portion removing step may be performed after the resin removing step.

For example, the remaining film portion 4b shown in FIG. 1I is removed by a method such as dry etching. At this time, in order to prevent the protruding electrode 7 from being etched together with the remaining film portion 4b, the upper portion of the protruding electrode 7 may be masked before etching.

As a result, only the projecting electrodes 7 are formed on the seed layer 3, as shown in FIG. Therefore, the problem described in the second embodiment can be similarly resolved.

(Embodiment 4)
A fourth embodiment of the present disclosure will be described.

In Embodiment 1, by using the imprint mold 5 having the conical or pyramidal concave portion 5a (see FIG. 1B), the truncated conical or pyramidal projection electrode 7 (see FIG. 1I) is formed. Although the case has been described as an example, the shape of the projecting electrode 7 is not limited to this. Examples of the shape of the projecting electrode 7 are shown in FIGS. 4A to 7D.

For example, the projecting electrode 7a shown in FIG. 4A has a two-stage structure. The upper and lower stages of the projecting electrodes 7a are cylindrical or prismatic, respectively. In order to form the protruded electrodes 7a, an imprint mold 5 having recesses having the same shape or substantially the same shape as the protruded electrodes 7a is used in the process of forming the protruded electrodes.

For example, the projecting electrode 7b shown in FIG. 4B has a two-stage structure. The upper stage of the projecting electrode 7b has a truncated cone shape or a truncated pyramid shape, and the lower stage of the projecting electrode 7b has a cylindrical or prismatic shape. In order to form the protruded electrodes 7b, an imprint mold 5 having recesses having the same shape or substantially the same shape as the protruded electrodes 7b is used in the process of forming the protruded electrodes.

For example, the projecting electrode 7c shown in FIG. 4C has a two-stage structure. The upper and lower stages of the projecting electrode 7c are respectively shaped like a truncated cone or a truncated pyramid. In order to form the protruded electrodes 7c, an imprint mold 5 having recesses having the same shape or substantially the same shape as the protruded electrodes 7c is used in the process of forming the protruded electrodes.

For example, a projecting electrode 7d shown in FIG. 4D has a three-step structure. The upper, middle, and lower portions of the protruding electrode 7d are each shaped like a truncated cone or a truncated pyramid. In order to form the protruding electrodes 7d, an imprint mold 5 having recesses having the same shape or substantially the same shape as the protruding electrodes 7d is used in the process of forming the protruding electrodes.

The shape of the projecting electrodes 7a to 7d described above may be appropriately selected in consideration of, for example, the shape of the electrode pad 2 and stress absorption during mounting of the semiconductor device.

As described above, in the present embodiment, by using the imprint mold 5 having recesses having the same shape or substantially the same shape as the shape of the projected electrode to be formed, the desired shape of the projected electrode can be stably formed. can do. Therefore, the present embodiment is advantageous in terms of the stability and limitation of the shape of the protruded electrodes as compared with the case where the protruded electrodes are formed by photolithography.

It should be noted that the present disclosure is not limited to the description of each of the above embodiments, and various modifications are possible without departing from the scope of the present disclosure.

The method of manufacturing a semiconductor device according to the present disclosure can stably form a plurality of projecting electrodes on a semiconductor element, and is useful for manufacturing semiconductor devices that are becoming smaller, have more pins, and have narrower pitches.

REFERENCE SIGNS LIST 1 semiconductor element 2 electrode pad 3 seed layer 4 soluble ultraviolet curing resin 4a projection 4b residual film portion 5 imprint mold 5a recess 6 plating resistant resin 6a cavity 7, 7a, 7b, 7c, 7d projection electrode 11 silicone substrate 12 insulation Film 13 Aluminum pad 14 Protective film 15 Barrier metal 16 Bump 17 Resist

Claims (5)

a resin forming step of coating a surface of a semiconductor element including a plurality of electrode pads with a cured resin;
a projection forming step of forming projections of the cured resin on the electrode pads and curing the projections;
a resin supply step of coating the protrusion with a plating solution resistant resin;
a resin exposing step of exposing a portion of the protrusion on the surface of the plating solution resistant resin by removing a portion of the plating solution resistant resin;
a dissolving step of forming a hollow portion in the plating solution resistant resin by removing the cured resin corresponding to the protrusion;
a plating step of filling the cavity with plating;
and a resin removal step of removing the plating solution resistant resin.
A method of manufacturing a semiconductor device. In the projection forming step,
forming the projection by pressing a transfer mold having a shape corresponding to the projection onto the cured resin;
2. The method of manufacturing a semiconductor device according to claim 1. In the projection forming step,
forming the protrusion after heating the cured resin;
3. The method of manufacturing a semiconductor device according to claim 1. Further comprising a residual film portion removing step of removing a residual film portion of the cured resin, which is a portion other than the protrusion,
4. The method of manufacturing a semiconductor device according to claim 1. The residual film removing step includes:
performed after the protrusion forming step or after the resin removing step,
5. The method of manufacturing a semiconductor device according to claim 4.

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